Flooding in Oregon

On this page you learn what types of flooding are typical in Oregon and how do you protect yourself, your family and your home. You can also find out more about significant Oregon floods. Finally, you'll find links to NWS offices that provide forecast and safety information for Oregon, as well as links to our partners who play a significant role in keeping you safe.

Significant Oregon
Floods

The Heppner Flood of 1903

This was the most deadly natural disaster in Oregon's recorded history. A strong thunderstorm, bringing extremely heavy rain and hail, approached Heppner, OR. The storm covered a very small area, probably no more than 50 square miles. Heavy rain fell in a short time, creating severe flash flooding along Willow Creek, normally a peaceful stream flowing through the town center. The entire town was swept away in just a few short minutes, drowning about 247 people. Eyewitnesses say they saw a 40-foot wall of water and the ensuing flood raged through town for over an hour. In all, one-third of the towns' structures were destroyed. The massive runoff of water was a result of heavy rain falling on the barren rocky hills, then flowing into the Willow Creek watershed. Only about 15 minutes separated the first rainwater in Willow Creek at Heppner and the flood crest. There are no rainfall records available for this storm because the weather observing station was completely destroyed, drowning the observer and his entire family. Bodies of some of those killed in the flood were washed as far as 40 miles downstream to the Columbia River.

A similar fate would have been in store for the citizens of Ione, just 20 miles downstream. Although 150 homes were destroyed, telephoned warnings prompted an immediate evacuation and Ione residents escaped to high ground.

Flash flood sweeps through Heppner, Oregon on June 14, 1903

Vanport Memorial Day Flood of 1948

The Columbia River at Vancouver crest at 30 feet, the highest stage since the late 1800s, and the discharge was about 1 million cubic feet per second for almost a month. Vanport was constructed in 1943 to house families of workers at the wartime Kaiser Shipyard. A poorly constructed levee surrounding the community failed dramatically at 4 pm on May 30, rapidly inundating and destroying Vanport. At least 15 people died in the flood, and the city was a complete loss. Flooding also occurred in several other communities downstream of Portland/Vancouver on both the Oregon and Washington banks of the river.

Record Stages:
Columbia River at Vancouver: 30.8 feet on 6/1/1948, 31.0 feet on 6/13/1948
Willamette River at Portland: 30.0 feet on 6/1/1948

December 1964 Christmas Flood

Record amounts of rain fell on low-elevation snow and frozen ground. Major flooding was widespread. For many basins in Oregon, the flood peaks during this winter event remain the record. The flod claimed 17 people in Oregon and caused hundreds of millions of dollars in damage. By the end of the flood, almost every river in Oregon had flooded and more than 30 major bridges were impassable. Numerous landslides added to the damage and impacts.

This was a classic rain-on-snow flood. Heavy snow blanketed much of the state December 17-19, followed by a rapid transition to a warm, moist air mass. Rainfall totals December 20-24 were 10-20 inches in western Oregon and 5- 15 inches in central and eastern Oregon. Several inches (water-equivalent) of snowmelt added to the runoff, and areas of frozen ground increased the surface runoff.

February 1996 Flood

In February 1996, Widespread major flooding affected the entire Pacific Northwest and was especially notable in western Oregon and Washington. Several rivers, especially in the northern Willamette Valley, set new record stages. The flooding was the culmination of a series of unusual weather events:

First, the fall and winter had above-normal precipitation, about 125 percent above normal, although snowpack was below normal.

Second, in mid and late January, tremendous amounts of snow fell in mid and high elevations of the Cascades and coastal mountains, and significant snow accumulated even at low elevations.

Third, the period of snow was followed by a deep freeze, with freezing rain, frost, and frozen ground.

Fourth, the weather pattern changed dramatically in early February, with a strong subtropical jet (“pineapple express”) bringing warm, moist air to the region, which resulted in very heavy rain and rapid snowmelt.

December 1996 / January 1997 Flood

Although this flood event was not as major and damaging as the February 1996 flood, it was widespread and caused significant damage throughout Northern California and the Pacific Northwest. The event was the result of warm, subtropical moisture with heavy rain and snowmelt. Oregon river basins most impacted included the Rogue (southwest Oregon) and Tualatin (northwest Oregon). Precipitation totals for December 20, 1996 through January 3, 1997, were 8 to 16 inches in western Oregon. There were 3 deaths caused by the flooding.
Record Stages:
Imnaha River at Imnaha - Maximum discharge, 20,200 feet3/s Jan. 1, 1997, gage height, 11.44 feet

Flash Flooding

Flash flooding is a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event (i.e., intense rainfall, dam failure, ice jam). More information...

River Flooding

River flooding occurs when river levels rise and overflow their banks or the edges of their main channel and inundate areas that are normally dry. More information...

Tropical Systems and Coastal Flooding

At any time of year, a storm from over the ocean can bring heavy precipitation to the U.S. coasts. Whether such a storm is tropical or not, prolonged periods of heavy precipitation can cause flooding in coastal areas, as well as further inland as the storm moves on shore. More information...

Burn Scars/Debris Flows

Wildfires burn away the vegetation of an area, leaving behind bare ground that tends to repel water. When rain falls, it runs off a burn scar towards a low lying area, sometimes carrying branches, soil and other debris along with it. Without vegetation to hold the soil in place, flooding can produce mud and debris flows. More information...

Ice/Debris Jams

A back-up of water into surrounding areas can occur when a river or stream is blocked by a build-up of ice or other debris. Debris Jam: A back-up of water into surrounding areas can occur when a river or stream is blocked by a build-up of debris. More information...

Snowmelt

Flooding due to snowmelt most often occurs in the spring when rapidly warming temperatures quickly melt the snow. The water runs off the already saturated ground into nearby streams and rivers, causing them to rapidly rise and, in some cases, overflow their banks.More information...

Dry Wash

When heavy rain falls over extremely dry land, the water rushes towards low-lying areas, which may include dried up canyon or river beds. This can quickly turn a dry channel into a raging river.More information...

Dam Breaks/Levee Failure

A break or failure can occur with little to no warning. Most often they are caused by water overtopping the structure, excessive seepage through the surrounding ground, or a structural failure. More information...